A typical liquid crystal display is capable of displaying a clear and sharp image through millions of pixels that make up the complete image. The liquid crystal display has thus been applied to various electronic equipment in which messages or pictures need to be displayed, such as mobile phones and notebook computers. However, liquid crystals in the liquid crystal display do not themselves emit light. Rather, the liquid crystals have to be lit up by a light source so as to clearly and sharply display text and images. The light source may be ambient light, or a backlight module attached to the liquid crystal display.
Referring to FIGS. 11, 12 and 13, a typical backlight module 1 generally includes a metal tray 11 having supporting portions 111, a light source reflector 13 having a U-shaped cross-section, a light source assembly 14, a light guide plate 16 disposed on the metal tray 11, a reflective plate 15 disposed below the light guide plate 16, a diffusing plate 17 disposed above the light guide plate 16, and a plastic frame 12. The plastic frame 12 cooperates with the metal tray 11 to accommodate the U-shaped light source reflector 13, the light source assembly 14, the reflective plate 15, the light guide plate 16, and the diffusing plate 17. The light guide plate 16 includes a light incident surface 161 perpendicular to the metal tray 11, and a side surface 162 which is also perpendicular to the metal tray 11 and which perpendicularly adjoins the light incident surface 161. The side surface 162 includes a plurality of protrusions 163 extending perpendicularly outwardly therefrom. The supporting portions 111 of the metal tray 11 correspond to respective gaps defined between adjacent protrusions 163 of the light guide plate 16. That is, the supporting portions 111 can cooperate with the protrusions 163 to fix the light guide plate 16 to the metal tray 11. The light source assembly 14 is located adjacent to the light incident surface 161 of the light guide plate 16. The light source assembly 14 includes a linear light source 141, a pair of fasteners 142 for fastening the light source 141 in the light source reflector 13, and a plurality of O-shaped rings 143 nested on the light source 141 for protecting the light source 141.
If the backlight module 1 is subjected to shock or jarring, action and reaction forces occur between the metal tray 11 and the light guide plate 16. Because the protrusions 163 of the light guide plate 16 cooperatively fit with the supporting portions 111 of the metal tray 11, action and reaction forces therebetween may cause the metallic supporting portions 111 to cut the protrusions 163 or even break the protrusions 163 off from a main body of the light guide plate 16. If the protrusions 163 are no longer held in place by the supporting portions 111, the light guide plate 16 is liable to collide with and cause damage to the light source 141. Thus the reliability of the backlight module 1 may not be satisfactory, particularly in higher-risk applications and during transportation.
Therefore, a new backlight module that can overcome the above-described problems is desired.